Heat damage (concrete pavement)
A heat damage (or heat departure ) is a pothole , by long-lasting high temperatures in concrete pavements occurs under certain conditions. These are spalling or bulging of individual concrete deck slabs. Sudden pushing or kinking of the panels ("blow up") is also possible. In the media, this event is also referred to as "road blast". On the other hand, such damage cannot occur on asphalt roads .
Heat damage occurs in rare numbers on older concrete pavements that have been heated up considerably due to a prolonged period of heat and at the same time meet certain requirements (see section “Causes”). In the particularly hot summers of 2003 and 2013 in particular, concrete slabs suddenly buckled on several German motorways, such as the A 93 in Bavaria, causing serious accidents.In 2015, a blow-up was observed on the A1 in the canton of St. Gallen become.
process
The effect of solar radiation increases the temperature of the concrete deck slabs on the top and causes thermal expansion . The bottom, on the other hand, remains cooler and is less stretched than the top, resulting in a bulging of the plate. The expansion initially only reduces the joint space between the individual concrete slabs. If no further expansion is possible, compressive stresses occur in the plates . These compressive stresses continue to increase as the temperature rises and can be absorbed by the concrete slab up to a certain point. This point is particularly dependent on the manufacturing quality and thickness of the concrete slabs, but it can also be negatively influenced by traffic loads. If a deck can no longer absorb the compressive stresses, it will be destroyed or suddenly buckled.
causes
Heat damage is due to production-related and maintenance-related defects in the concrete pavement.
The following manufacturing-related defects can cause heat damage:
- insufficient compaction or too high a void content of the concrete
- Insufficient thickness of the concrete pavement
- Inadequate bonding with multi-layer construction
- Incorrectly executed construction joint
The following maintenance-related defects can cause heat damage:
- Replacement or filling of defective concrete slabs with or with asphalt (so-called "asphalt seals")
- neglected care of the joints
Countermeasures
There are various countermeasures to prevent heat damage to concrete pavements as much as possible. Concrete ceilings must have a certain minimum thickness in relation to their length in order to be able to absorb compressive stresses from the effects of heat without buckling. Furthermore, joint renovation must be carried out regularly when maintaining concrete pavement. Filling damaged concrete slabs with asphalt also has a very negative effect and should be limited to short-term temporary solutions.
literature
- Velske, S., Mentlein, H .: Road construction technology . Werner Verlag, Düsseldorf 2002, ISBN 3-8041-3875-6 .
Web links
- Guide to dealing with heat damage to concrete pavements (PDF; 540 kB)
- Leaflet - The construction of concrete pavements on roads (PDF; 800 kB)
Individual evidence
- ↑ Regina Brand, Sascha Gorhau: Deadly ski jump. In: Süddeutsche Zeitung . June 20, 2013. Retrieved July 29, 2013 .
- ↑ www.20minuten.ch, 20 minutes, 20 minutes, www.20min.ch: Heat makes the highway asphalt crack open . In: 20 minutes . ( 20min.ch [accessed on September 19, 2018]).